Alkyl mercapto substituted amino benzoic acid alkamine amides, salts, intermediates,and process of preparing same



Patented Nov. 5, 1946 ALKYL MERCAPTO SUBSTITUTED AMINO BENZOICACID ALKAMINE AMIDES, SALTS, INTERMEDIATES; AND PROCESS OF PRE- PARING SAME John J. Donleavy, Montclair, N. J., assignor to Allied Laboratories, Inc., Kansas City, M0.

N Drawing. Application April 24, 1943, Serial No. 484,472

This invention relates to a newly discovered group of organic compounds which have a local anesthetic action similar to :.cocaine or procaine and the like.

This'application is a continuation-in-part'of the co-pending application Serial No. 282,352 filed January 1, 1939(now Patent No. 2,321,468), and entitled Alkyl thio substituted amino benzoic acid alkamine esters, salts, intermediate and process of preparing same, in turn a continuation-in-partof Patent No. 2,173,827, dated September 26, 1939.

The chief object of this invention is to prepare a compound which ha local anesthetic properties equal or greater than that of cocaine, etc, and which has a toxicity equal to or less than that of the last mentionedproducts, the anesthetic property of the present newly discovered organic compounds being of local character. Specifically the products are amides and comparable to the esters of the application hereinbefore referred 'to and now allowed.

An amide of the examples hereinafter mentioned was found to have approximately four times the anesthetic power of cocaine although only having a toxicity equal to that of cocaine and to that extent this amide is more suitable for anesthetic purposes-than the esters of the co-pending application, which included an example that showed onl twice the anesthetic power of cocaine for the best comparable ester product. The products herein of amide character have the general, form expressed algebraically as follows:

RfSCsI-Ia (NI-I2) CONH(CH2) INR' 'R, wherein R is an alkyl radical, R," is an alkyl radical and R is an alkyl radical and r is an integer greater than the unity and less than 4. In certain instance R," and R' may be combined in the form of a polymethylene chain, for examplethe group NR"R' may be the piperidyl radical.

Broadly speaking, the product is an amide of an aromatic acid and a dialkyl amino alkyl amine, or is a salt thereof.

Inasmuch as the aforementioned allowed application, now Patent. No. 2,321,468, dated September 26, 1939; fully and accurately sets forth in considerable detail the highly desirable characteristics of the general class of products to which that disclosure and the instant disclosure is directed, no further description or explanation is believed necessary.

It may be here briefly stated that the first two 5 Claims. (01. 260558)' as originally filed, are processes which followed to a certain point produce intermediates but thereafter the processes are changed herein and there are produced amides having the advantages before mentioned over the esters produced by the process of that co-pending disclosure.

By way of explanation only it is stated that common to the Patent No. 2,173,827, and the copending application disclosure, now Patent No. 2,321,468, and the instant application all the products include the introduction of an alkyl meroapto group into molecules previously known to have some anesthetic power, but such introduction in the products of the co-pending application disclosure, now'Patent No. 2,321,468, were more desirable for reasons stated therein over the products of the earlier patent and in comparable manner the products of the instant disclosure (the amides, etc.) are more desirable than the esters, eta, set forth in the copending application,-

now Patent No. 2,321,468.

The formula of this subsequent specific. disclosure is set forth as follows for one compound of one series of compounds:

, In the series of compounds, the CONI-ICHzCI-IzN' (C2H5)2 may vary in position and the SC2H5 may vary in position relative to each other and, the position of NI-Ia. Also in place of (CzHs), wherever the same appears, other alkyl groups may be substituted therefor. One example of the species group represented by the preceding diagram is:

Dialkylamino alkyl amides of 3-dmino-4- lkylmercaptol-benzoic acids As representatives of this type there have been prepared the beta-diethylaminoalkyl amide of 3- amino .4 methylmercaptobenzoic, 3 amino-4- ethylmercaptobenzoic and 3-amino-4-propylmercaptobenzoic acids.

A convenient method of preparing compounds of this type depends on the discovery that the chlorine atom of derivatives of 3-nitrochloro- 'benzoic acid such as its salts, esters and amides can readily be replaced by an alkylmercapto group by treatment with a metal mercaptide, the products being the corresponding derivatives of 3-nitro-4-alkylmercaptobenzoic acids. Subsequently the nitro group'may be converted to an 5 acid, B. P. 180 C. at 4 mm.; the methyl ester of 3-amino-4-n-propylmercaptobenzoic acid, B. P. 182 at 5 mm.; the corresponding beta-diethylaminoetliyl amide dihydrochlorides M. P. 149- 151 C. and 145-149" C. respectively: in both cases the free amides were again oils, which did not crystallize.

Method II A solution of 2.1 grams of the methyl ester of 3-nitro-l-ch1oro-benzoic acid in 30 cc. of 95% a1- cohol was heated to boiling and added to a boiling solution of sodium methyl mercaptide, prepared by bubbling one gram of methyl mercaptan slowly into a solution of 0.4 gram of sodium hydroxide in a mixture of 3 cc. of water and 30 cc. of 95% alcohol. The total mixture was boiled under reflux for thirty minutes. The solvent was then removed by distillation under diminished pressure and the solid residue was washed with 15 cc. of water containing a drop of hydrochloric acid. The product, the methyl ester of 3-m'tro lmethylmercaptobenzoic acid, was purified by recrystallization from methyl alcohol.

Further procedure following this method is identical with that applied to the same compound in Method I. Method II, therefore, is an alternative method of preparing the intermediate.

In connection with the beta-diethylaminoethylamide of 3-amino-4-ethylmercaptobenzoic acid used for the production of the dihydrochlorid in a similar manner as before mentioned, same produced the corresponding dihydrochloride wherein the actual nitrogen yield was 11.36% compared with the theoretical nitrogen yield of 11.44% and the ionizable chlorine found was 18.80% as compared to the calculated amount of 19.07%.

The beta-diethylaminoethyl amide of 3-aminoi-N-propylmercaptobenzoic acid when used to prepare the dihydrochloride thereof in a comparable manner produced a product which upon analysis was found to contain nitrogen in the amount of 11.09%, whereas the theoretical nitrogen content was 11.02%.

While the invention has been described in great detail in the foregoing specifications the same is to be considered as illustrative only of the general claims and not restrictive in character. Modifications here-of comparable to those disclosed in the earlier Patent No. 2,173,827, as well as in the co-pending application, now Patent No. 2,321,468, as well as others which will readily suggest themselves to persons skilled in this art, are to be considered as within the scope of this invention, reference being had to the appended claims ior the definition thereof.

The present disclosure is intended as a basic disclosure of basic compounds previously described and the related compounds which differ in the position of the groups in the benzene ring.

Herein the general disclosure 'is directed to compounds comprising as a Markush group the amides and the acid addition compounds of said amides and wherein said amides have the general formula, RS (NI-I2) CeI-Is CONH (CI-12M NR" R" where x is an integer greater than unity and less than four and R, R and R represent alkyl radicals of like or unlike character.

The invention claimed is:

1. An organic compound having the formula para-RS-meta-NI-IzCeHaCONH(CH2) eNR' 'R' where a: is an integer greater than one and less than four and R, R" and R represent alkyl radicals containing not more than six carbon atoms.

2. S-Diethylaminoethyl amide of 3-amino-4- (n-propylmercapto) benzoic acid.

3. p-Diethylaminoethyl amide of 3-amino-4- (ethylmercapto) benzoic acid.

4. p-Diethylaminoethyl amide of 3-amino-4- (methylmercapto) benzoic acid.

5. The method of preparing a 3-nitro-4-(alkylmercaptolbenzoic acid by heating a sodium mercaptide and the sodium salt of a 3-nitro-4- chlorobenzoic acid in aqueous alcohol solution.

JOHN J. DONLEAVY. 

